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Finding the Fourth Proportional to 821.21, 1,230.75 and 430.22

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Solution

The fourth proportional to 821.21, 1,230.75 and 430.22 is: 644.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.21 : 1,230.75 = 430.22 : x
  2. Step 2: Convert to fraction form
    821.21/1,230.75 = 430.22/x
  3. Step 3: Cross multiply
    821.21x = 1,230.75 × 430.22
  4. Step 4: Simplify right side
    821.21x = 529,491.11
  5. Step 5: Solve for x
    x = 529,491.11/821.21
  6. Step 6: Final answer
    x = 644.77

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.